It is well known that proteins may be attached to surfaces, typically by covalent attachment of the protein directly to the solid substrate, or by covalent attachment to polymers that had previously been attached to the surface, or by physical entrapment of the protein into pores within the solid surface itself, or by simple adsorption. of the protein to the surface of the microarray. Although such means of attachment allow for a higher concentration of protein, there is a loss in functionality due to chemical modification of the surface. Sol-gels have been used to entrap proteins on solid supports. However, acceptable sol-gels are limited to those without undesirable properties of gelling in the pin during printing, irreproducible spot sizes cracking, poor adhesion, incompatibility with entrapped components, or reducing activity of the entrapped protein. None of these methods of attachment or entrapment enable site-addressable, self-assembly of a 3 dimensional protein structure on a microarray.
Thus, there is a recognized need in the art for improved formulations and methods for physically entrapping protein on a microarray surface without direct attachment, binding or adsorption to the surface. Specifically, the prior art is deficient in aqueous crosslinkable formulations comprising Oligo-dT and protein(s) that can be entrapped and preserved in a native protein state in a high concentration on the microarray. The present invention fulfills this longstanding need and desire in the art.